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curl/lib/curl_sasl_gssapi.c

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/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 2014, Steve Holme, <steve_holme@hotmail.com>.
*
* This software is licensed as described in the file COPYING, which
* you should have received as part of this distribution. The terms
* are also available at http://curl.haxx.se/docs/copyright.html.
*
* You may opt to use, copy, modify, merge, publish, distribute and/or sell
* copies of the Software, and permit persons to whom the Software is
* furnished to do so, under the terms of the COPYING file.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
* RFC4752 The Kerberos V5 ("GSSAPI") SASL Mechanism
*
***************************************************************************/
#include "curl_setup.h"
#if defined(HAVE_GSSAPI) && defined(USE_KERBEROS5)
#ifdef HAVE_OLD_GSSMIT
#define GSS_C_NT_HOSTBASED_SERVICE gss_nt_service_name
#define NCOMPAT 1
#endif
#define GSSAUTH_P_NONE 1
#define GSSAUTH_P_INTEGRITY 2
#define GSSAUTH_P_PRIVACY 4
#include <curl/curl.h>
#include "curl_sasl.h"
#include "urldata.h"
#include "curl_base64.h"
#include "curl_gssapi.h"
#include "curl_memory.h"
#include "sendf.h"
#define _MPRINTF_REPLACE /* use our functions only */
#include <curl/mprintf.h>
/* The last #include file should be: */
#include "memdebug.h"
/*
* Curl_sasl_build_gssapi_spn()
*
* This is used to build a SPN string in the format service@host.
*
* Parameters:
*
* serivce [in] - The service type such as www, smtp, pop or imap.
* host [in] - The host name or realm.
*
* Returns a pointer to the newly allocated SPN.
*/
static char *Curl_sasl_build_gssapi_spn(const char *service, const char *host)
{
/* Generate and return our SPN */
return aprintf("%s@%s", service, host);
}
/*
* Curl_sasl_create_gssapi_user_message()
*
* This is used to generate an already encoded GSSAPI (Kerberos V5) user token
* message ready for sending to the recipient.
*
* Parameters:
*
* data [in] - The session handle.
* userp [in] - The user name.
* passdwp [in] - The user's password.
* service [in] - The service type such as www, smtp, pop or imap.
* mutual_auth [in] - Flag specifing whether or not mutual authentication
* is enabled.
* chlg64 [in] - Pointer to the optional base64 encoded challenge
* message.
* krb5 [in/out] - The gssapi data struct being used and modified.
* outptr [in/out] - The address where a pointer to newly allocated memory
* holding the result will be stored upon completion.
* outlen [out] - The length of the output message.
*
* Returns CURLE_OK on success.
*/
CURLcode Curl_sasl_create_gssapi_user_message(struct SessionHandle *data,
const char *userp,
const char *passwdp,
const char *service,
const bool mutual_auth,
const char *chlg64,
struct kerberos5data *krb5,
char **outptr, size_t *outlen)
{
CURLcode result = CURLE_OK;
size_t chlglen = 0;
unsigned char *chlg = NULL;
OM_uint32 gss_status;
OM_uint32 gss_major_status;
OM_uint32 gss_minor_status;
gss_buffer_desc spn_token = GSS_C_EMPTY_BUFFER;
gss_buffer_desc input_token = GSS_C_EMPTY_BUFFER;
gss_buffer_desc output_token = GSS_C_EMPTY_BUFFER;
(void) userp;
(void) passwdp;
if(krb5->context == GSS_C_NO_CONTEXT) {
/* Generate our SPN */
char *spn = Curl_sasl_build_gssapi_spn(service,
data->easy_conn->host.name);
if(!spn)
return CURLE_OUT_OF_MEMORY;
/* Populate the SPN structure */
spn_token.value = spn;
spn_token.length = strlen(spn);
/* Import the SPN */
gss_major_status = gss_import_name(&gss_minor_status, &spn_token,
gss_nt_service_name, &krb5->spn);
if(GSS_ERROR(gss_major_status)) {
Curl_gss_log_error(data, gss_minor_status, "gss_import_name() failed: ");
return CURLE_OUT_OF_MEMORY;
}
}
else {
/* Decode the base-64 encoded challenge message */
if(strlen(chlg64) && *chlg64 != '=') {
result = Curl_base64_decode(chlg64, &chlg, &chlglen);
if(result)
return result;
}
/* Ensure we have a valid challenge message */
if(!chlg) {
infof(data, "GSSAPI handshake failure (empty challenge message)\n");
return CURLE_BAD_CONTENT_ENCODING;
}
/* Setup the challenge "input" security buffer */
input_token.value = chlg;
input_token.length = chlglen;
}
gss_major_status = Curl_gss_init_sec_context(data,
&gss_minor_status,
&krb5->context,
krb5->spn,
&Curl_krb5_mech_oid,
GSS_C_NO_CHANNEL_BINDINGS,
&input_token,
&output_token,
mutual_auth,
NULL);
Curl_safefree(input_token.value);
if(GSS_ERROR(gss_major_status)) {
if(output_token.value)
gss_release_buffer(&gss_status, &output_token);
Curl_gss_log_error(data, gss_minor_status,
"gss_init_sec_context() failed: ");
return CURLE_RECV_ERROR;
}
if(output_token.value && output_token.length) {
/* Base64 encode the response */
result = Curl_base64_encode(data, (char *) output_token.value,
output_token.length, outptr, outlen);
gss_release_buffer(&gss_status, &output_token);
}
return result;
}
/*
* Curl_sasl_create_gssapi_security_message()
*
* This is used to generate an already encoded GSSAPI (Kerberos V5) security
* token message ready for sending to the recipient.
*
* Parameters:
*
* data [in] - The session handle.
* chlg64 [in] - Pointer to the optional base64 encoded challenge message.
* krb5 [in/out] - The gssapi data struct being used and modified.
* outptr [in/out] - The address where a pointer to newly allocated memory
* holding the result will be stored upon completion.
* outlen [out] - The length of the output message.
*
* Returns CURLE_OK on success.
*/
CURLcode Curl_sasl_create_gssapi_security_message(struct SessionHandle *data,
const char *chlg64,
struct kerberos5data *krb5,
char **outptr,
size_t *outlen)
{
CURLcode result = CURLE_OK;
size_t chlglen = 0;
size_t messagelen = 0;
unsigned char *chlg = NULL;
unsigned char *message = NULL;
OM_uint32 gss_status;
OM_uint32 gss_major_status;
OM_uint32 gss_minor_status;
gss_buffer_desc input_token = GSS_C_EMPTY_BUFFER;
gss_buffer_desc output_token = GSS_C_EMPTY_BUFFER;
unsigned int indata = 0;
unsigned int outdata = 0;
gss_qop_t qop = GSS_C_QOP_DEFAULT;
unsigned int sec_layer = 0;
unsigned int max_size = 0;
gss_name_t username = GSS_C_NO_NAME;
gss_buffer_desc username_token;
/* Decode the base-64 encoded input message */
if(strlen(chlg64) && *chlg64 != '=') {
result = Curl_base64_decode(chlg64, &chlg, &chlglen);
if(result)
return result;
}
/* Ensure we have a valid challenge message */
if(!chlg) {
infof(data, "GSSAPI handshake failure (empty security message)\n");
return CURLE_BAD_CONTENT_ENCODING;
}
/* Get the fully qualified username back from the context */
gss_major_status = gss_inquire_context(&gss_minor_status, krb5->context,
&username, NULL, NULL, NULL, NULL,
NULL, NULL);
if(GSS_ERROR(gss_major_status)) {
Curl_gss_log_error(data, gss_minor_status,
"gss_inquire_context() failed: ");
Curl_safefree(chlg);
return CURLE_OUT_OF_MEMORY;
}
/* Convert the username from internal format to a displayable token */
gss_major_status = gss_display_name(&gss_minor_status, username,
&username_token, NULL);
if(GSS_ERROR(gss_major_status)) {
Curl_gss_log_error(data, gss_minor_status, "gss_display_name() failed: ");
Curl_safefree(chlg);
return CURLE_OUT_OF_MEMORY;
}
/* Setup the challenge "input" security buffer */
input_token.value = chlg;
input_token.length = chlglen;
/* Decrypt the inbound challenge and obtain the qop */
gss_major_status = gss_unwrap(&gss_minor_status, krb5->context, &input_token,
&output_token, NULL, &qop);
if(GSS_ERROR(gss_major_status)) {
Curl_gss_log_error(data, gss_minor_status, "gss_unwrap() failed: ");
gss_release_buffer(&gss_status, &username_token);
Curl_safefree(chlg);
return CURLE_BAD_CONTENT_ENCODING;
}
/* Not 4 octets long so fail as per RFC4752 Section 3.1 */
if(output_token.length != 4) {
infof(data, "GSSAPI handshake failure (invalid security data)\n");
gss_release_buffer(&gss_status, &username_token);
Curl_safefree(chlg);
return CURLE_BAD_CONTENT_ENCODING;
}
/* Copy the data out and free the challenge as it is not required anymore */
memcpy(&indata, output_token.value, 4);
gss_release_buffer(&gss_status, &output_token);
Curl_safefree(chlg);
/* Extract the security layer */
sec_layer = indata & 0x000000FF;
if(!(sec_layer & GSSAUTH_P_NONE)) {
infof(data, "GSSAPI handshake failure (invalid security layer)\n");
gss_release_buffer(&gss_status, &username_token);
return CURLE_BAD_CONTENT_ENCODING;
}
/* Extract the maximum message size the server can receive */
max_size = ntohl(indata & 0xFFFFFF00);
if(max_size > 0) {
/* The server has told us it supports a maximum receive buffer, however, as
we don't require one unless we are encrypting data, we tell the server
our receive buffer is zero. */
max_size = 0;
}
/* Allocate our message */
messagelen = sizeof(outdata) + username_token.length + 1;
message = malloc(messagelen);
if(!message) {
gss_release_buffer(&gss_status, &username_token);
return CURLE_OUT_OF_MEMORY;
}
/* Populate the message with the security layer, client supported receive
message size and authorization identity including the 0x00 based
terminator. Note: Dispite RFC4752 Section 3.1 stating "The authorization
identity is not terminated with the zero-valued (%x00) octet." it seems
necessary to include it. */
outdata = htonl(max_size) | sec_layer;
memcpy(message, &outdata, sizeof(outdata));
memcpy(message + sizeof(outdata), username_token.value,
username_token.length);
message[messagelen - 1] = '\0';
/* Free the username token as it is not required anymore */
gss_release_buffer(&gss_status, &username_token);
/* Setup the "authentication data" security buffer */
input_token.value = message;
input_token.length = messagelen;
/* Encrypt the data */
gss_major_status = gss_wrap(&gss_minor_status, krb5->context, 0,
GSS_C_QOP_DEFAULT, &input_token, NULL,
&output_token);
if(GSS_ERROR(gss_major_status)) {
Curl_gss_log_error(data, gss_minor_status, "gss_wrap() failed: ");
Curl_safefree(message);
return CURLE_OUT_OF_MEMORY;
}
/* Base64 encode the response */
result = Curl_base64_encode(data, (char *) output_token.value,
output_token.length, outptr, outlen);
/* Free the output buffer */
gss_release_buffer(&gss_status, &output_token);
/* Free the message buffer */
Curl_safefree(message);
return result;
}
/*
* Curl_sasl_gssapi_cleanup()
*
* This is used to clean up the gssapi specific data.
*
* Parameters:
*
* krb5 [in/out] - The kerberos 5 data struct being cleaned up.
*
*/
void Curl_sasl_gssapi_cleanup(struct kerberos5data *krb5)
{
OM_uint32 minor_status;
/* Free our security context */
if(krb5->context != GSS_C_NO_CONTEXT) {
gss_delete_sec_context(&minor_status, &krb5->context, GSS_C_NO_BUFFER);
krb5->context = GSS_C_NO_CONTEXT;
}
/* Free the SPN */
if(krb5->spn != GSS_C_NO_NAME) {
gss_release_name(&minor_status, &krb5->spn);
krb5->spn = GSS_C_NO_NAME;
}
}
#endif /* HAVE_GSSAPI && USE_KERBEROS5 */
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